The present embodiments relate to producing a radiation treatment plan as part of planning the irradiating of diseased tissue with a treatment beam.
Radiation therapy is among the established methods employed in the treatment of tumorous diseases. Radiation therapy entails directing beams onto a target volume within a body. The target volume may be irradiated. Within the scope of particle therapy, which is a particular form of radiation therapy, for example, protons, carbon ions, and other ions are accelerated to high energies and directed onto the tissue requiring to be irradiated. However, other types of beams, for example, electron beams and x-rays, can be used for irradiation. Irradiating methods, which are used in radiation or particle therapy, may be used in non-therapeutic domains. The non-therapeutic domains include, for example, research conducted within the scope of particle therapy on non-living phantoms or bodies and the irradiating of materials.
To irradiate a target volume as accurately as possible, the treatment beam should deliver energy only within the target volume. Surrounding tissue should be spared. To achieve delivery of energy only within the target volume, a radiation treatment plan precisely defining the parameters based on which irradiating is to take place is usually produced before a target volume is irradiated.
Owing to various factors it may not be possible to precisely plan and predict the irradiating of a target volume in every detail. The irradiation can deviate slightly from the ideal irradiating that has been planned. Reasons for the deviation include moving of the target volume, lack of precision in the target volume's positioning relative to the treatment beam, lack of precision during planning, and changes occurring within the target volume between planning and treatment.
Attempts are made to take the lack of precision and imponderables into account during planning so that as good as possible irradiating results. For example, a safety margin around the target volume may be set so that it will always be irradiated adequately.
The conference paper titled “Factors affecting the selection of beam directions in proton therapy”, Lomax T, 44th AAPM Annual Meeting, Montréal, July 2002, Abstract ID 7798, discloses that an index by which density heterogeneities are quantified is able to predict the magnitude of effects that can impair a treatment plan.
The publication by Pflugfelder D et al. titled “Quantifying lateral tissue heterogeneities in hadron therapy”, Medical Physics, 2007, 34(4), 1506-1513, discloses a method for quantifying lateral tissue heterogeneities in a scanned particle beam. Applied particle beams are each individually rated by an index and the multiplicity of indices employed in optimizing irradiation planning.